Project

Amory Lovins Uber Solar Home (Colorado)

At about 8,000 feet elevation, Rocky Mountain Institute founder Amory Lovins' house (RMI's original headquarters) serves as an office and a showcase for green architecture and ultra-efficient housing. Though it was built in 1984, it was renovated and now includes additional solar panels that allow the building to produce more energy than it uses. The house is filled with a series of systems that are designed to get the most out of the building, and to make the space as liveable as possible. Lovins is apparently fond of saying that people who live in energy-efficient houses need not skimp on hot showers or cold beer. The Snowmass, Colorado-based Rocky Mountain Institute is a non-profit dedicated to promoting sustainability in three main areas: Energy, transportation and green buildings. Read below for Jeffrey Ball's article from the Wall Street Journal. (Scroll to bottom for additional resources.)

Wall Street Journal - A quarter-century ago, in the wake of America's first energy crisis, a young scientist named Amory Lovins came to the Rocky Mountains and built himself a radical house based on a radical idea. The country could save both energy and money, he believed, by combining common sense and unconventional technology.

Mr. Lovins did achieve substantial energy savings, and many of his innovations, from better insulation to multiple-pane windows to more-efficient refrigerators, eventually became familiar fixtures in American homes.

But on the second part of Mr. Lovins's ambition -- saving money -- the calculus has been more complicated. The advances that allowed him to create a roomy home with a tiny carbon footprint came with a hefty upfront cost.

Now, Mr. Lovins has completed a renovation that he hopes will demonstrate how much more energy-efficient houses can become. But the project also serves as a reminder of the still-enormous gulf between what is technologically possible and what society is able or willing to pay for.

The 4,000-square-foot structure Mr. Lovins and his then-wife completed in 1984 looked part-cave and part-spaceship. Its 16-inch-thick stone walls kept the interior temperature fairly constant. A book-lined interior was dimly lighted with electricity from solar panels on the roof. The greenhouse that formed the central living room let in light, and it stored heat in a small jungle of plants, from guavas to coffee to bananas.

The house, which Mr. Lovins dubbed the "Banana Farm," used one-tenth the energy of a typical U.S. house of its size. Lower utility bills quickly offset the higher construction costs, saving money on heating and cooling within a year.

Since then, Mr. Lovins has become perhaps the world's most famous apostle of energy efficiency. The recipient of a MacArthur Foundation "genius grant," he co-founded the Rocky Mountain Institute, an energy and environmental think tank that has consulted with companies including Wal-Mart Stores and Ford Motor.

Energy efficiency expert Amory Lovin is putting the finishing touches on a state-of-the-art green home that produces more energy than it consumes. Jeffrey Ball reports from Aspen, Colorado.

Having seen many features the Banana Farm helped pioneer trickle down to the consumer market, the 61-year-old Mr. Lovins hopes his latest efficiency moves eventually will find widespread acceptance as well.

Most studies suggest energy efficiency is the cheapest way to start meaningfully limiting pollution by curbing growth in fossil-fuel use -- far cheaper than generating more wind or solar power.

A report last month by McKinsey & Co. concluded that the U.S. could cut its energy use 23% below the projected U.S. demand level in 2020 by boosting efficiency, and save $1.2 trillion in energy costs. But that would require immediately making expensive investments in new equipment. Other countries have subsidized and mandated those steps, and the U.S. is beginning to follow suit. But a recession is a tough time to make big changes.

Mr. Lovins is "pushing the envelope of what's possible," but "that's probably a step too far for what's practical," says Scott Nyquist, head of the global energy practice at McKinsey, which has worked with Mr. Lovins on research projects.

Mr. Nyquist is renovating his own 1930s-era house in Houston, in part to test what energy-efficiency goals are feasible and affordable. He decided that some features championed by Mr. Lovins, such as light-emitting-diode lights, remain far too expensive. "I'm being disciplined," Mr. Nyquist says. "I'm trying a different approach than Amory is."

Banana Farm 2.0, as Mr. Lovins calls his updated digs, was renovated largely with equipment donated by individuals and companies eager to be associated with the project. Mr. Lovins says he doesn't know what the two-year renovation would have cost had he had to pay the full tab. But just a few of the major items would put the retail cost of the project well beyond $150,000.

On a recent afternoon, Mr. Lovins climbed up onto his home's flat roof, an easy task because the back of the house is built into the side of a hill to take advantage of the earth's insulating power.

Laid across the roof are devices designed to capture solar energy: photovoltaic panels that convert sunlight into electricity, thermal panels that use the sun's warmth to heat water, and clear plastic tubes that funnel sunlight down into the house, where it illuminates the central hallway.

A bank of new photovoltaic panels nearly doubles the amount of solar electricity the house produces, to 9.7 kilowatts, enough for the house's needs. The panels, which were donated to Mr. Lovins, retail for about $30,000, not including installation, though tax breaks cut that price significantly.

"We are making no economic claims for Banana Farm 2.0," he says. "We deliberately brought in a bunch of cutting-edge, even bleeding-edge, stuff." Instead, he thinks that with the right government policies to spur market demand, even the most advanced green modifications could make economic sense. His role, as he sees it, is to push the limits of technology.

"Demand is the sum of a lot of negligible individual actions," he says. "When there are a lot of individuals, it isn't negligible. It adds up."

Banana Farm 2.0 isn't combustion-free. A wood-burning stove still sits near Mr. Lovins' office -- a backup heat source he hopes to abandon if the house works as planned this winter. But the new solar panels have allowed him to get rid of two devices that burned gas: a stove and a water heater.

Some of his proudest advances stem from mundane changes. He installed an electric stove made by a Swiss company that is 60% more efficient than other models he found. The savings stem partly from pots designed specifically for the stove. The pots eliminate warping that typically occurs with copper cookware, wasting heat.

He also has shaved energy use by insisting on an unconventional plumbing design. Typically, residential pipes that carry water would be ½-inch wide and turn at right angles. But that builds up friction, requiring electric pumps to work harder to propel the water. So Mr. Lovins had three-quarter-inch-wide pipes installed that run diagonally across ceilings and walls to minimize friction.

"If it looks pretty," he says, "it probably doesn't save energy."

For now, Banana Farm 2.0 is a showcase of what is technologically possible. Adopting some of the house's innovations on a wide scale would require huge investment and sweeping changes to governmental policy.

Still, Mr. Lovins knows that some of the most effective ways to reduce fossil-fuel use don't require groundbreaking science. As he headed out to dinner in his hybrid car on a recent evening, the Banana Farm's owner did something decidedly low-tech: He turned off the lights.

Building Strategies from RMI:The 4,000-square-foot building is superinsulated and solar-heated. The building's designers wanted to create a building that was so good at capturing and retaining heat that it could offer livable conditions without a furnace.

It was insulated to double the requirements of the Pitkin County building code at the time of construction. The structure was also oriented to the south to better collect solar radiation, and it was built with a "tight" thermal envelope. While a less weather-tight house might experience a complete air change every hour, this building experiences a complete air change every ten hours or so (with the ventilators turned off, or up to considerably more than one air change per hour if they're all turned on).

The building is almost entirely lit by daylight. Its curved walls dampen interior noises and a central greenhouse humidifies the interior. These amenities make the building comfortable, and have significantly cut power demand and operational costs.

Glazing Much of the building's thermal performance is due to its advanced windows (often called "superwindows"), which were used here commercially for the first time. Virtually all are heavy-gas-filled Heat Mirror® windows. Heat Mirror® is a 0.002-inch (50-µm) clear polyester film with special, almost atomically thin, coatings that are transparent to visible light but reflect infrared (heat) rays.

The film is suspended between glass panes in a double-paned window unit and performs the way a third pane would perform—only better, because it keeps in more heat and lets in more light than a third piece of glass would. In fact, the type of Heat Mirror® film originally used in RMI's windows (Heat Mirror® 88, designed to maximize solar heating in cold climates) loses only about one-tenth as much heat as a single pane of glass, and lets in three-quarters of the visible light and half of the total solar energy.

During the 1990s, most of our building's original argon-filled, single-Heat Mirror® units were replaced with krypton-filled units having a double-sided film (Heat Mirror® coated on each side of a single suspended polyester film), and in some units supplemented by a low-emissivity (heat-reflecting) coating inside the outer lite of glass. The building's window configurations vary, but their light-reflecting and insulating capacities are keys to its efficiency.

The latest reglazing, in 2005–09, uses xenon fill and achieves center-of-glass R-values of 12.5 for all units except three that achieve R-20.0 via six selective surfaces.

Walls The stone used in the walls is Dakota sandstone slabs harvested from the hillside a half-mile north of the site and hauled to the site in an old pickup truck. The walls were built using a technique called "slipforming," developed by architect Frank Lloyd Wright.

A pair of parallel, curving plywood forms was erected; insulating central foam, rebar, and any needed conduits, drains, structural pillars, etc. were placed inside; stones were placed inside up against the interior and exterior forms, and concrete was added in hand-scoops to fill in the space between the central foam layer and the forms, gradually building up each twenty-inch-high layer of masonry. When the forms were removed, excess concrete was removed with trowels, and the stones were washed. Overnight curing of the concrete permitted the forms to be raised twenty inches the next day in preparation for another "slip" the following day. The walls are constructed of two six-inch layers of this type of masonry with a four-inch layer of insulating foam sandwiched between.

Increasing insulation value in a house is one of the easiest and most cost-effective ways to save energy. These walls have an effective R-value of forty (~0.056 k), nearly double that of the wall of a conventional residential house. On the north side of the building, a solid concrete wall is predominately underground or "earth-bermed," which also helps to temper heat flow out of the building. The roof has an R-value of about eighty.

Tracking Photovoltaic Panels The solar electric, or photovoltaic, panels on the building's roof turn sunlight into electricity for use inside the building. There are two PV panels at the west end of the building. They use tracking mechanisms to keep the panels pointed at the sun. Small electric motors turn the panels every few minutes (when you stand near them you can see and hear them turn). By tracking the sun, these PV panels (also called arrays) collect about 30–40 percent more energy than they would if they were stationary. The tracking mechanisms are turned off at night because they are so sensitive they would track the moon.

A 2009 modernization added a 6-kW Sunpower array on the east roof and made the PV system islandable, so it runs with or without the grid. Ordinarily it sells back surplus solar power to the grid to displace coal. At night, the building runs on certified-additional purchased windpower.

Photovoltaic Panels The lower, main section of roof has two adjustable-tilt rows of photovoltaics (each with five panels apiece). These PVs don't track the sun, but they are raised and lowered seasonally to catch the sun's rays at better angles. They generate up to about two kilowatts of electricity. Their average annual output, about one-fourth as large, meets roughly a third of the building's electricity needs, nearly all of which are for the RMI office. Advances in PV technology enable today's panels to be much less conspicuous than these; indeed, modern PVs are designed so well they can be used as wall and roofing material.

Solar Hot Water System There is a row of solar panels near the northern edge of the roof. They are one part of a system that heats water for domestic use. The water is first pre-warmed to about 68–105°F (19–40°C) as it passes through pipes in the concrete arch in the greenhouse below. These roof-mounted panels heat the lower layers of water stored in a 1,500-gallon tank under a closet in the residential part of the building. When someone turns on a faucet, water pre-heated in the greenhouse arch is drawn through a copper pipe immersed at the top of the tank, to which the hottest storage water rises. This secondary heat exchanger normally heats the domestic water to about 140°F (60°C). If needed, perhaps after a long period of winter cloud, a renewable-electric boiler in the workshop adds the last few degrees.

In 2009, the solar hot-water system was expanded to distribute hot water to radiant coils cast into the concrete floor slabs in 1983 but not previously connected. This is hoped to displace the woodstoves, which normally provide the last ~1% of space heating energy but were not used in the winter of 2009.

Between 1982 and 1984, more than 100 volunteers and a dozen professional builders helped RMI cofounder Amory Lovins construct a state-of-the art energy-efficient home in Old Snowmass, Colo.

The house would draw almost all of its space and water-heat from solar energy, use about a tenth the usual amount of household electricity, and grow bananas passively over 7,000 feet above sea-level in the Rocky Mountains.

Way ahead of its time then, this private residence and RMI headquarters has just leaped forward another twenty years.

We are in the last throes of a major renovation of Amory's landmark home.

The project will have taken almost a year.

It could have been finished sooner, Amory says, save for the constant introduction of new ideas and technology for improvements and modernization.

Let me run through some of the major changes.

The building's photovoltaic system has been supplemented with a 6-kilowatt array of the most efficient solar panels on the market, courtesy of SunPower.

The system will be one of the first to be "islandable" -- able to run gracefully with or without the grid.

With new batteries sucking up the extra electricity, the house will have several days worth of energy stored. The building will also have two of the most efficient residential air-to-air heat exchangers ever constructed, capturing heat from the interior to heat incoming fresh air with peak flow efficiency around 95 percent and average efficiency close to 100 percent.

As Amory likes to say, "In God we trust, all others bring data." A total of 140 sensor points will feed a new Johnson Controls data acquisition system.

Information on solar power generation, electricity flows, and internal and external climate conditions will be available online, and to all visitors via a screen in the building's entryway. The data will allow the building's occupants and admirers to have a much better sense of the building's performance, and how to correct any problems.

Other updates include new xenon-filled windows (supplied by Alpen Glass at cost) with R-14 (or for one unit R-19) center-of-glass insulating value, improved insulation and air tightening, an LED-dominated fifth lighting retrofit, a daylighting retrofit, radiant solar floor heating, and a new highly efficient electric stove integrated with specially designed pots to save around 60 percent of the energy normally needed for cooking.

In 1983, the focus of the house was to use as little primary energy as possible, but our clearer understanding of climate change has altered Amory's set of design priorities to save carbon first, and primary energy second.

"This building is not a museum of 1983 state-of-the-art efficiency technologies," Amory says about his domicile.

"My objective now is to show the current stat-of-the-art, and to displace as much carbon as I can."

Since electric consumption peaks in the winter in the Rocky Mountains, the new solar panels are angled to maximize winter output and displace the most coal from inefficient intermediate load power plants.

At night, the house will run on 'additional' windpower built from our purchase.

Why be on the grid and use windpower rather than the stored solar battery power?

"We're already on the grid so we can sell back surplus electricity to save more carbon.

The reason we buy wind at night, use solar in the day, and stored solar only for backup when the grid is down is to displace the maximum amount of carbon. If we used stored solar at night we would pay for the in-out cycle loss from the batteries, which would amount to less solar to displace coal," Amory says.

Amory states the house will be fossil-fuel-free (no nonrenewable grid electricity or propane) and could be 'combustion-free' by the end of the remodel, though that remains to be seen.

So, what lessons can Joe Homeowner take from these renovations?

"Whether you're building or remodeling, go to the state-of-the-art technology and integrative design. You'll get many benefits from each expenditure and your building will work better, be a nicer place to live, and cost less," Amory says.